Continuing charity is sadaqah jariyah like a well that gives water, a school that continues to educate, knowledge that others benefit from is the time you've spent with others who have learnt from your character, your education and how you spread Islam. It is also books you have written or a school you have helped funded. Finally, a righteous child who prays for their parents is the final legacy that continues to benefit a person. May Allah allow us to accumulate good deeds while alive and leave behind this legacy of three so that we benefit from them after we have gone too - Ameen!